1. Field of the Invention
The present invention relates to techniques for assessing skin exposure to contaminants, such as toxic chemicals or the like.
2. Description of the Prior Art
Skin exposure constitutes an important route of entry into the human body for a large number of toxic chemicals. Circumstances may exist where absorption through the skin may equal or exceed the amount of chemical taken in through inhalation over a given period of time, such as an eighthour workday. Toxic contaminants may either affect the skin itself or have systemic toxicity, the extent of the effect depending upon the physical and chemical properties of the contaminant, the anatomical area of contact, the duration of contact and inter-personal variability, as well as environmental conditions. Various decontamination procedures have been adopted for certain workplace environments to remove contaminants from the skin, but it is first necessary to detect the presence of the contaminant on the skin to determine whether decontamination procedures are called for.
Methods previously used to assess skin exposure to toxic chemicals in the workplace include visual examination of the skin for discoloration or other visible effects, the use of an absorbent pad placed next to the skin to collect contaminants during the workday, and testing of the skin by wiping or washing it to remove and collect contaminant materials therefrom. Visible examination of the skin may not be effective in many cases where skin change does not occur until after a considerable length of time or after the cumulative effects of a number of periods of exposure. A major limitation of prior wiping and absorbent pad collection techniques is the requirement for laboratory analysis of the skin wipe or absorbent pad for contamination, which results in delayed reporting of results and increased costs.
Thus, for example, in U.S. Pat. No. 4,706,676, there is disclosed a dermal substance collection device for removing substances from the skin for later analysis. Similarly, in U.S. Pat. No. 2,890,797, there is disclosed a device having a circular region for absorbing a collected material and a contiguous peripheral region to which the collected material migrates for later testing by adding suitable solvents or the like to the peripheral region.
It is also known to provide indicator devices for immediate on-site indication of the presence of a substance. Thus, for example, U.S. Pat. No. 3,715,192 discloses an indicator strip which has a capillary material impregnated with the reagents and is confined between impermeable layers, being open only along its peripheral edges for directly absorbing a liquid medium to be examined for reaction with the impregnated reagents to give a color change or other indication of the presence in the liquid of the contaminant of interest. But this device is useful only with contaminants which are already in liquid media which can be easily absorbed up through the very small exposed surface area at the edge of the indicator strip. Furthermore, dirt or other foreign material in the liquid medium being tested may interfere with detection of the contaminant of interest.